.container {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;

  /* 这会使容器占据整个视口的高度，实现垂直居中 */
  .box {
    display: flex;
    flex-direction: column;
    /* 垂直分布 */
    align-items: center;
  }
}